Electrostatic chuck member and method of producing the same

ABSTRACT

It is to provide an electrostatic chuck member having a strong adsorption force and an excellent responsibility (release property) in the stop of voltage application and is an electrostatic chuck member comprising a substrate, an undercoat of a metallic layer formed on at least one surface thereof, a lower insulating layer of Al 2 O 3  ceramic formed on the undercoat, a metallic electrode layer formed on the lower insulating layer and an upper insulating layer of Al 2 O 3  ceramic formed on the electrode layer as a topcoat.

TECHNICAL FIELD

[0001] This invention relates to an electrostatic chuck member used whena conductive member, a semiconductive member, an insulative member orthe like is held at adsorption state by static electricity, and a methodof producing the same.

BACKGROUND ART

[0002] Recently, treatments such as dry etching, ion implantation, CVD,PVD and the like constituting a part of a production process forsemiconductor or liquid crystal display, e.g. a production device ofsemiconductors changes from a wet process into a dry process fromviewpoints of automation and anti-pollution. A greater part of thetreatment through the dry process is usually carried out under vacuum orin an atmosphere under a reduced pressure.

[0003] In such a dry process treatment, it is required to improve apositioning accuracy in the formation of patterns on a substrate such asa silicon wafer, a glass plate or the like from viewpoints of highintegration of circuits and fine work.

[0004] As a method satisfying such a demand, vacuum chuck or mechanicalchuck has hitherto been utilized in the transportation, adsorption andfixation of the substrate. However, since the vacuum chuck is used undervacuum, the pressure difference is not made large and the adsorptionforce is weak. Even if the substrate can be adsorbed, an adsorbingportion becomes local and strain is caused in the substrate.Furthermore, the gas cooling can not be carried out with the temperaturerising in the treatment of the wafer, so that the vacuum chuck can notbe applied to the recent production process of high-performancesemiconductor devices. On the other hand, the mechanical chuck becomescomplicated in the structure and takes a long time in the maintenanceand inspection thereof.

[0005] In order to avoid the above drawbacks of the conventionaltechnique, electrostatic chuck utilizing static electricity is recentlydeveloped and widely adopted. However, this technique has the followingproblems.

[0006] When the substrate is adsorbed and held by such an electrostaticchuck, charge retains between the substrate and the electrostatic chuck(through the action of adsorption force) even after the applied voltageis topped, so that the detaching of the substrate can not be carried outunless the charge is completely removed.

[0007] For this end, it has been attempted to improve the insulatingdielectric material used in the electrostatic chuck. For example, thereare the following proposals:

[0008] {circle over (1)} JP-A-6-8089 discloses an example of using asintered body or a spray coating of a mixture of aluminum nitride powderand titanium nitride powder as a high insulative material;

[0009] {circle over (2)} JP-A-6-302677 discloses that titanium oxide isapplied onto a surface of the high insulative material and aluminum isapplied thereto to contact with Si+SiC plate;

[0010] {circle over (3)} JP-B-6-36583 discloses an example usingaluminum oxide as a high insulative material;

[0011] {circle over (4)} JP-A-5-235152 and JP-A-6-8089 disclose thataluminum oxide, aluminum nitride, zinc oxide, quartz, boron nitride,sialon and the like are used as a high insulative material;

[0012] {circle over (5)} JP-A-3-147843 and JP-A-3-204924 disclose amethod wherein volume resistivity is lowered to improve staticelectricity by adding TiO₂ having a high dielectric constant to the highinsulative material in case of further requiring a higher staticelectricity;

[0013] {circle over (6)} The high insulative material of Al₂O₃ or thelike containing TiO₂ has a drawback that adsorption force remains for aninterim even after the power source is switched off. As a techniqueovercoming this drawback, therefore, JP-A-11-111826, JP-A-11-69855 andthe like disclose a method wherein a polarity of an electrode isreversed for shortening a detaching time of a silicon wafer;

[0014] {circle over (7)} JP-A-8-64663 discloses a method wherein acoating having a conductivity is formed on a part of an insulating layerfor rapidly conducting the detaching of the silicon wafer;

[0015] {circle over (8)} JP-A-8-330403, JP-A-11-26564 and the likedisclose an electrostatic chuck member having a water-cooling structurefor preventing temperature rise of the electrostatic chuck in theoperation and the lowering of performances accompanied therewith.

[0016] However, a Al₂O₃—TiO₂ based high insulative spray-coated layerused in the electrostatic chuck has the following problems to be solved.

[0017] (1) In the Al₂O₃ based spray-coated layer mixed with TiO₂, thevolume resistivity is small and a slight current flows, so that it canbe expected to improve the static electricity through Jensen-Rahbekeffect (A. Jensen & K. Rahbek s force). However, since TiO₂ is asemiconductor substance, the moving rate of electrical charge is slowand the responsibility (arrival time of saturated adsorption, adsorptiondisappearing time) when the application of voltage is stopped is poor,and this responsibility becomes more remarkable under low-temperatureenvironment.

[0018] In order to render the value of volume resistivity into, forexample, a practical state of 1×10⁹ Ω·cm, it is necessary to add about25 wt % of TiO₂. In the production process of semiconductors, however,the addition of a great amount of TiO₂ means the incorporation ofimpurity, which brings about the degradation of quality and results inthe contamination of working environment.

[0019] Furthermore, when the temperature of the semiconductor wafer tobe adsorbed is higher than room temperature, there is a high possibilitythat a large leak current is passed to break wafer circuit because thevolume resistivity is too low.

[0020] (2) The Al₂O₃.TiO₂ based spray-coated layer is formed by aspraying process. In the coating obtained by this method, however, thevolume resistivity and adsorption force are largely scattered and alsothe productivity is low to bring about the rise of the cost.

[0021] It is, therefore, a main object of the invention to provide anelectrostatic chuck member having a large volume resistivity, a smallscattering thereof and a good quality.

[0022] It is another object of the invention to provide an electrostaticchuck member having a strong adsorption force and an excellentresponsibility (release property) in the stop of voltage application.

[0023] It is the other object of the invention to provide a spray-coatedlayer for an electrostatic chuck member without TiO₂ damaged by contactwith a silicon wafer, a physical erosion action through plasma or achemical erosion action through a halogen compound included in anenvironment and fearing a pollution of environment.

[0024] It is a still further object of the invention to propose asubstitute technique for overcoming such a drawback that theconventional Al₂O₃ insulative substrate produced by the sinteringprocess is easily damaged by a temperature change in a use environment.

[0025] It is a yet further object of the invention to form a greaterpart of not only an insulating layer but also an electrode by a sprayingmethod to develop a high productivity, a good coating adhesion propertyand an excellent static electricity for overcoming drawbacks inherent tothe conventional electrostatic chuck member formed by spraying a ceramicaround a metal electrode.

DISCLOSURE OF THE INVENTION

[0026] An electrostatic chuck member according to the invention isformed by laminating a metallic electrode layer and an insulating layerof an oxide ceramic having an electric resistance onto a surface of ametal substrate through spraying.

[0027] That is, a basic construction of the invention is anelectrostatic chuck member comprising a substrate, a metallic undercoatformed on at least one surface thereof, a lower insulating layer ofAl₂O₃ ceramic formed on the undercoat, a metallic electrode layer formedon the lower insulating layer and an upper insulating layer of Al₂O₃ceramic formed on the electrode layer as a topcoat.

[0028] In the invention, the metallic undercoat is a spray-coated layerhaving a thickness of 30-300 μm, and each of the lower insulating layerand the upper insulating layer is a spray-coated layer having athickness of 100-500 μm, and the metallic electrode layer is aspray-coated layer having a thickness of 5-100 μm and is favorable tohave an oxygen amount included in the metallic electrode layer of notmore than 2.0 wt % and a porosity of 1-7%.

[0029] Each of the lower and upper insulating layers made of Al₂O₃ceramic is preferable to be formed by spraying a spraying materialpowder having a purity of not less than 98.0 wt % so as to render theporosity into a range of 1-8%.

[0030] It is favorable that at least one surface of each of the lowerinsulating layer and the upper insulating layer is sealed byimpregnating an organic or inorganic silicon compound and a volumeresistivity of such a layer is within a range of 1×10¹³-1×10¹⁵ Ω·cm.

[0031] The metallic electrode layer is favorable to be formed using atleast one spraying material selected from W, Al, Cu, Nb, Ta, Mo, Ni andalloys containing at least one of these metallic elements.

[0032] The metallic undercoat applied between the substrate and thelower insulating layer of Al₂O₃ ceramic for improving a bonding forcetherebetween is favorable to be formed by using at least one sprayingmaterial selected from Ni, Al, Cr, Co, Mo and an alloy containing atleast one of these metallic elements.

[0033] The upper insulating layer of Al₂O₃ occupied as a topcoat in anoutermost surface layer portion of the electrostatic chuck memberaccording to the invention is preferable to be finished a contact facewith a silicon wafer supported thereon to a surface roughness Ra: about0.1-2.0 μm by mechanical working.

[0034] As a spraying process used in the production of the electrostaticchuck member according to the invention, any one of low-speed andhigh-speed flame spraying process, arch spraying process, atmosphereplasma spraying process, plasma spraying process under a reducedpressure, explosion spraying process and the like may be used in theformation of the metallic undercoat. On the other hand, it is favorableto adopt atmosphere plasma spraying process, plasma spraying processunder a reduced pressure or the like in the formation of the Al₂O₃ceramic insulating coated-film.

[0035] Although the example of film formation is described by limitingonly the spraying process in the invention, it is possible to conductsimilar film-forming means such as CVD, PVD, ion implantation and thelike, if necessary.

BRIEF DESCRIPTION OF THE DRAWING

[0036]FIG. 1 is a diagrammatic view illustrating a sectional structureof an electrostatic chuck according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0037] An example of producing an electrostatic chuck according to theinvention through a spraying process will be described below.

[0038] At first, a surface of a metal substrate is subjected to a blasttreatment and subsequently to a roughening treatment, and then ametallic spraying material is sprayed onto a surface of the thus treatedsubstrate to form an undercoat. On the undercoat is formed a lowersprayed insulating layer of Al₂O₃ ceramic by a spraying process. Andalso, a metallic sprayed electrode layer is formed on a surface of thelower sprayed insulating layer, preferably so as to leave a peripheraledge portion by a spraying process, which is ready in use as anelectrode. Further, an upper sprayed insulating layer is formed on themetallic sprayed electrode layer by spraying Al₂O₃ ceramic. In this way,an electrostatic chuck member having a lamination structure as shown inFIG. 1 is produced.

[0039] When the metallic sprayed electrode layer is sandwiched betweenthe sprayed insulating layers of Al₂O₃ ceramic from up and down, initialperformances can be maintained over a long time without being affectedby corrosive gas in the environment or plasma even under any useenvironment.

[0040] It is preferable that a diameter of the metallic sprayedelectrode layer is used to be at least 5 mm smaller than a diameter ofeach of the upper and lower insulating layers of Al₂O₃ ceramic in orderthan the end face of the electrode is not exposed to an exterior.

[0041] In FIG. 1, numeral 1 is a metal substrate, numeral 2 an undercoatmade of a metallic sprayed layer, numeral 3 a lower sprayed insulatinglayer of Al₂O₃ ceramic, numeral 4 a metallic sprayed electrode layer,numeral 5 an upper sprayed insulating layer of Al₂O₃ ceramic as atopcoat, numeral 6 a silicon wafer, numeral 7 a direct current source,numeral 8 a ground, and numeral 9 a copper wire for application ofvoltage. Each film (layer) from the undercoat 2 to the topcoat 5 isformed by the spraying process. Moreover, numeral 10 is a place directlycontacting Al₂O₃ ceramic sprayed insulating layers of the upper sprayedinsulating layer 3 and the lower sprayed insulating layer 5 with eachother.

[0042] As a spraying material for forming the metallic undercoat 2, oneor more of metals such as Ni, Al, Cr, Co, Mo and the like and alloysthereof are suitable, and a thickness thereof is preferably 30-300 μm,particularly 50-150 μm. When the thickness is less than 30 μm, the filmbecomes non-uniform, while when it exceeds 300 μm, the improvement ofthe function as the undercoat is not particularly recognized and such athickness is unfavorable in view of economical reason and operation.

[0043] The upper sprayed insulating layer and the lower sprayedinsulating layer of Al₂O₃ ceramic formed on the undercoat 2 andpositioned up and down on the metallic sprayed electrode layer 4 so asto sandwich therebetween are required to have excellent electricinsulating property, corrosion resistance and resistance to plasmaerosion. For this purpose, these layers are required to be high in thepurity and dense. According to the inventors experiments, it has beenconfirmed that the purity is preferable to be not less than 98%,particularly not less than 99% and the porosity of the sprayed film ispreferable to be within a range of 1-8%, particularly 1-5%.

[0044] And also, the thickness of each of the upper-lower sprayedinsulating layers of the Al₂O₃ ceramic is preferably within a range of100-500 μm. When it is less than 100 μm, the electric insulatingproperty is not sufficient, while when it exceeds 500 μm, the remarkableeffect is not obtained and it is not economical.

[0045] Preferably, it is 130-400 μm.

[0046] The metallic sprayed electrode layer formed on the surface of thelower sprayed insulating layer is desirable to be formed by spraying oneore more selected from W, Al, Cu, Nb, Ta, Mo, Ni and alloy containingone or more of these metals. And also, the thickness is preferablewithin a range of 5-100 μm. When the thickness is less than 5 μm, thelayer becomes porous and the action and function as the electrode lower,while when it exceeds 100 μm, the considerable improvement of thecharacteristics as the electrode is not recognized and it isuneconomical. Particularly, a range of 10-30 μm is preferable.

[0047] The porosity of the sprayed electrode layer is favorable to besmaller. It has been confirmed that there is not particularly caused aproblem when the porosity in the film formed by the spraying process iswithin a range of 1-8%. Moreover, when the porosity is not more than 1%,it is difficult to form the film in an atmosphere by spraying. While,when the porosity exceeds 7%, the temperature of the electrode layer isunfavorably raised by heat generation through the penetration ofcorrosive gas included in the atmosphere or increase of electricresistance in the application of voltage.

[0048] In case of the sprayed electrode layer, an oxide film producedwhen the metal is sprayed in the atmosphere is an electrically resistantsource and is not favorable. According to the experimental result, it ishas been confirmed that an amount of not more than 2.0 wt % included isnot particularly trouble as a sprayed electrode layer. In the inventionis formed the sprayed electrode layer having an oxygen content of notmore than 2.0 wt %.

[0049] Then, it is preferable that the upper sprayed insulating layer ofAl₂O₃ ceramic formed on an outermost layer as a topcoat is polished soas to be parallel to the surface of the metal substrate and finished toa surface roughness Ra of 0.1-2.0 μm by machining (polishing).

[0050] Particularly, the finished surface of the mechanically polishedupper sprayed insulating layer is subjected to a sealing treatment byapplying a liquid organosilicon compound (organic silicon resin, forexample, methyl silyl triisocyanate, phenyl silyl triisocyanate) or aninorganic silicon compound (for example, silicon alkoxide compound,silicon compound of alkali metal) and heating at 120-350° C. for 1-5hours. By this sealing treatment is filled the silicon compound in finepore portions remaining in the sprayed layer, whereby the adhesion offoreign matter can be prevented and the invasion of corrosive gas fromoperating environment can be prevented. Moreover, the sealing treatmentmay be applied to the lower sprayed insulating layer of Al₂O₃ ceramic.

[0051] As mentioned above, the formation of the metallic sprayed layeras the undercoat, the metallic sprayed electrode layer, and the upperand lower sprayed insulating layers of Al₂O₃ ceramic can be conducted byusing a plasma spraying process, a high-speed flame spraying process, anexplosion spraying process, an arc spraying process (only the metallic)and the like, but the use of an atmospheric plasma spraying process or aplasma spraying process under a reduced pressure is particularlyfavorable in view of the productivity and the stability of quality.

EXAMPLE 1

[0052] After a one-side surface of an Al substrate (width 50 mm×length100 mm×thickness 5 mm) is roughened by blast treatment, 80 wt % Ni-20 wt% Al alloy is formed on the roughened surface at a thickness of 80 μm asan undercoat by a flame spraying process. On the undercoat is formedAl₂O₃ ceramic at a thickness of 150 μm by an atmosphere plasma sprayingprocess, and subsequently a metallic tungsten (W) is formed as a sprayedelectrode layer on the Al₂O₃ ceramic sprayed layer at a thickness of 60μm by an atmosphere plasma spraying process. Moreover, an oxygen contentin the electrode layer is 0.11 wt %. Then, an upper sprayed insulatinglayer of Al₂O₃ ceramic as a topcoat is formed on the surface of themetallic tungsten electrode layer by an atmosphere plasma sprayingprocess to form a test piece.

[0053] The thus prepared test piece is continuously left to stand underthe following corrosive environment for 200 hours to examine a state ofgenerating corrosion in the metallic tungsten electrode layer throughcorrosive component invaded from pore portions of the upper sprayedinsulating layer of Al₂O₃ ceramic as the topcoat.

[0054] (1) Test for spraying salt water (JIS Z2371)

[0055] (2) Test for resistance to halogen corrosion (the test piece isplaced in an atmosphere of a plastic corrosion testing apparatusintroduced with 120 ml/min of a mixed gas of CHF3 40 ml+Ar 60 ml,testing temperature 60° C.)

[0056] The results of the above corrosion test are shown in Table 1. Asseen from the results of Table 1, when the thickness of the uppersprayed insulating layer of Al₂O₃ ceramic is not less than 80 μm, thecorrosive component invading into the inside is shut even in the test ofspraying salt water and the test for the resistance to halogen corrosionand there is observed no sign of corrosion in the tungsten electrodelayer and the appearance just after the spraying is maintained. On thecontrary, when the thickness of the Al₂O₃ ceramic insulating layer is 50μm, 30 μm, the corrosive component invades through the pore portion toconsiderably corrode the tungsten electrode layer and the function as anelectrode tends to disappear. TABLE 1 Corrosion test resultsConstruction of film (after 300 h) Thickness Thickness Test for of ofupper resistance to electrode insulating Corrosion halogen No. layerlayer test corrosion Remarks 1 150 30 large color large colorComparative change by change by Example corrosion corrosion 2 150 50large color large color change by change by corrosion corrosion 3 150 80No problem No problem Invention 4 150 150 No problem No problem Example5 150 300 No problem No problem 6 150 500 No problem No problem

EXAMPLE 2

[0057] In this example, thermal shock resistance is tested with respectto the electrostatic chuck member according to the invention and asprayed layer around a metal electrode proposed in the prior art (e.g.JP-A-6-36583) as a comparative example.

[0058] (1) Layer Structure Adopted in the Electrostatic Chuck MemberAccording to the Invention

[0059] The following layers are formed on a one-side surface of Alsubstrate having a diameter of 100 mm and a thickness of 10 mm by usingatmosphere plasma spraying process and plasma spraying process under areduced pressure.

[0060] {circle over (1)} Undercoat: 80 wt % Ni-20 wt % Al at 100 μm byatmosphere plasma spraying process

[0061] {circle over (2)} Lower sprayed insulating layer: 99.5 wt % Al₂O₃at 150 μm by atmosphere plasma spraying process

[0062] {circle over (3)} Metallic electrode layer: a. metal W at 30 μmby atmosphere plasma spraying process

[0063] b. metal W at 30 μm by plasma spraying process under a reducedpressure

[0064] {circle over (4)} Upper sprayed insulating layer: 99.5 wt % Al₂O₃at 150 μm by atmosphere plasma spraying process

(2) LAYER STRUCTURE OF COMPARATIVE EXAMPLE

[0065] {circle over (1)} Undercoat: a. 80 wt % Ni-20 wt % Al at 100 μmby atmosphere plasma spraying process

[0066] b. no undercoat

[0067] {circle over (2)} Insulating layer: 99.5 wt % Al₂O₃ at 150 μm byatmosphere plasma spraying process

[0068] Moreover, the layer is coated onto a whole circumference of Alsubstrate having a diameter of 100 mm and a thickness of 10 mm in thecomparative example.

[0069] (3) Thermal Shock Test Conditions

[0070] When an operation that the member is heated in air at 350° C. for15 minutes and thereafter a compressed air of 25° C. is blown thereontofor 10 minutes is one cycle, the test of 10 cycles is conducted.

[0071] (4) Test Results

[0072] The results of the above test are shown in Table 2. As seen fromthese results, the layer of the comparative example sprayed on the wholecircumference of the Al substrate generates cracks in the test of 1-3cycles irrespectively of the presence or absence of the undercoat. Thisis considered due to the fact that there is a large difference inthermal expansion coefficient between the Al substrate and the Al₂O₃sprayed layer and the layer is formed on the whole circumference of thesubstrate to apply a large stress to the layer.

[0073] On the contrary, the layer satisfying the structure requirmentaccording to the invention maintains a sound state even after the testof 10 cycles and develops a high thermal shock resistance. TABLE 2Thermal shock Construction of film conditions Lower Metallic Upper 350°C. × 15 insulat- electrode insulat- min ⇄ cooling in No Undercoat inglayer layer ing layer air Remarks 1 presence presence presence* (1)presence No problem Compara- after 10 tive cycles Example 2 presencepresence presence* (2) presence No problem after 10 cycles 3 presenceabsence absence presence No problem Invention after 3 Example cycles 4absence absence absence presence No problem after 1 cycle

EXAMPLE 3

[0074] In this example, a change of residual adsorption force with alapse of time is examined when an operation is carried out by adsorbinga silicon wafer on the electrostatic chuck member and then a powersource is switched off.

[0075] (1) Layer Structure of Electrode Chuck Member Produced UnderConditions Suitable for the Invention

[0076] The following sprayed layers are formed on an Al substrate havinga diameter of 6 inches.

[0077] {circle over (1)} Undercoat: 80 wt % Ni-20 wt % Al 80 μm

[0078] {circle over (2)} Lower sprayed insulating layer: Al₂O₃ 150 μm

[0079] {circle over (3)} Metallic electrode layer: W 50 μm

[0080] {circle over (4)} Upper sprayed insulating layer: Al₂O₃ 150 μm

(2) LAYER STRUCTURE OF ELECTRODE CHUCK IN COMPARATIVE EXAMPLE

[0081] The following sprayed layers are formed on an Al substrate havinga diameter of 6 inches.

[0082] {circle over (1)} Undercoat: 80 wt % Ni-20 wt % Al 80 μm

[0083] {circle over (2)} Topcoat: 88 wt % Al₂O₃-12 wt % TiO₂ 300 μm

[0084] The measurement of residual adsorption force is carried out byapplying a voltage of 1 kV between a silicon wafer and an electrostaticchuck member in a vacuum vessel of 0.01 hpa for 1 minute and switchingoff a power source to measure the force (Pa) of peeling off the siliconwafer from the electrostatic chuck member.

[0085] As a result, in the electrostatic chuck member according to theinvention, the adsorption force is disappears just after OFF of thepower, while the electrostatic chuck member of Al₂O₃—TiO₂ in thecomparative example (prior art) is required to take 30-45 seconds forcompletely disappearing the adsorption force.

EXAMPLE 4

[0086] In this example, as the layers of the electrostatic chick memberaccording to the invention, after an Al substrate (width 50 mm×length 50mm×thickness 5 mm) is roughened by a blast treatment, 80 wt % Ni-20 wt %Al is formed at 70 μm by an arc spraying process, and Al₂O₃ is formedthereon at 180 μm by a plasma spraying process, and a metal W is formedthereon at 50 μm by a plasma spraying process, and Al₂O₃ is formedthereon at 200 μm by a plasma spraying process. Immediately after theformation of the layers, a commercially available liquid organic siliconresin is applied as a sealing agent and dried to obtain a test piece.

[0087] After the test piece is masked so as to expose a constant surface(10×10 mm), plasma is continuously discharged in a gas including ahalogen compound for 40 hours, and a loss quantity of the exposedportion due to plasma erosion is evaluated by a maximum loss thickness.

[0088] Test Conditions:

[0089] Gas composition CF₄ 100 ml+O₂10 ml+Ar 1000 ml

[0090] High frequency output 1200W

[0091] Pressure atmospheric pressure

[0092] Moreover, the test is carried out by using Al substrate subjectedto aluminizing treatment as a comparative example and the same layerstructure as in the invention except for an upper sprayed insulatinglayer of Al₂O₃+12 wt % TiO₂ of 200 μm under the same conditions.

[0093] As seen from the test results, the sprayed insulating layeraccording to the invention has an erosion quantity of about 12-15 μm,while the aluminized film of the comparative example is completelydisappeared and the Al substrate is damaged (50-70 μm), and theAl₂O₃+TiO₂ layer is observed to have a damage of 31-38 μm, from which itis understood that the electrostatic chuck member according to theinvention is very stable even in the plasma environment including thehalogen compound.

INDUSTRIAL APPLICABILITY

[0094] As mentioned above, the electrostatic chuck member according tothe invention is excellent in the corrosion resistance, thermal shockresistance and erosion resistance and can fix the silicon wafer only bya Coulomb force because the metallic sprayed electrode layer issandwiched between upper and lower Al₂O₃ ceramic sprayed insulatinglayers, so that the holding force immediately disappears in theswitch-off of the power source and the detaching of the silicon wafer orthe like is facilitated, which contributes to the improvement of theoperation efficiency.

[0095] And also, since the topcoat insulating layer is made of thesprayed film of Al₂O₃ ceramic, the electrostatic chuck member accordingto the invention has an excellent resistant force to abrasion action dueto the contact with the silicon wafer or plasma erosion action andprevents the fine pulverization of the sprayed layer components and ishigh in the chemical stability, so that it has an effect of controllingthe corrosion reaction with the environmental component (halogencompound and the like) to prevent the pollution of the environment.Furthermore, in the electrostatic chuck member according to theinvention, the metallic sprayed electrode layer is not directly exposedto the environment, so that it is less in the corrosion and modificationand maintains an excellent function over a long time and it can beexpected to efficiently conduct a precise working operation of anelectronic material member such as silicon wafer or the like in a higherquality. Moreover, the whole circumference of the metal electrode is notrequired to be covered with the insulating ceramic as compared with theconventional technique, so that the whole of the electrostatic chuck canbe miniaturized and the production steps can be considerably shortened.

[0096] In addition, the invention is particularly useful as a member tobe incorporated into a dry etching device, an ion implantation device, aCVD device, a PVD device or the like used in the production process ofsemiconductors and liquid crystals.

1. An electrostatic chuck member comprising a substrate, a metallicundercoat formed on at least one surface thereof, a lower insulatinglayer of Al₂O₃ ceramic formed on the undercoat, a metallic electrodelayer formed on the lower insulating layer and an upper insulating layerof Al₂O₃ ceramic formed on the electrode layer as a topcoat.
 2. Anelectrostatic chuck member according to claim 1, wherein the undercoatis a spray-coated layer having a thickness of 30-300 μm, and each of thelower insulating layer and the upper insulating layer is a spray-coatedlayer having a thickness of 100-500 μm, and the metallic electrode layeris a spray-coated layer having a thickness of 5-100 μm.
 3. Anelectrostatic chuck member according to claim 1, wherein the undercoatis a metallic layer formed by spraying one or more of Ni, Al, Cr, Co, Moand an alloy containing one or more of these metal elements.
 4. Anelectrostatic chuck member according to claim 1 or 2, wherein each ofthe lower and upper insulating layers is a layer formed by sprayingAl₂O₃ ceramic powder having a purity of not less than 98.0 wt % so as torender a porosity into 1-8%.
 5. An electrostatic chuck member accordingto claim 1, wherein at least one surface of each of the lower insulatinglayer and the upper insulating layer is sealed with an organic orinorganic silicon compound and has a volume resistivity within a rangeof 1×10¹³-1×10¹⁵ Ω·cm.
 6. An electrostatic chuck member according toclaim 1, wherein the metallic electrode layer is a layer formed byspraying one or more of W, Al, Cu, Nb, Ta, Mo, Ni and an alloycontaining one or more of these metal elements and has an oxygen contentof not more than 2.0 wt % and a porosity of 1-7%.
 7. A method ofproducing an electrostatic chuck member which comprises subjecting atleast one surface of a substrate to a blast treatment, spraying a metalor an alloy onto a roughened surface of the substrate to form anundercoat of a metallic layer, spraying Al₂O₃ ceramic onto the undercoatto form a lower insulating layer, spraying a metal onto the lowerinsulating layer to form a metallic electrode layer, further sprayingAl₂O₃ ceramic onto the metallic electrode layer to form an upperinsulating layer.
 8. A method of producing an electrostatic chuck memberaccording to claim 7 or 8, wherein the sealing treatment is carried outby applying a liquid organic or inorganic silicon compound to at leastone-side surface of the lower and upper insulating layers ormechanically polished surface and heating at 120-350° C. for 1-5 hours.9. An electrostatic chuck member according to claim 7, wherein theundercoat is sprayed at a thickness of 30-300 μm, and each of the lowerinsulating layer and the upper insulating layer is sprayed at athickness of 100-500 μm, and the metallic electrode layer is sprayed ata thickness of 5-100 μm.
 10. An electrostatic chuck member according toclaim 7, wherein the undercoat is formed by spraying one or more of Ni,Al, Cr, Co, Mo and an alloy containing one or more of these metalelements.
 11. A method of producing an electrostatic chuck memberaccording to claim 7, wherein each of the lower and upper insulatinglayers is formed by spraying Al₂O₃ ceramic powder having a purity of notless than 98.0 wt % so as to render a porosity into 1-8%.
 12. A methodof producing an electrostatic chuck member according to claim 7, whereinat least one surface of each of the lower insulating layer and the upperinsulating layer is sealed with an organic or inorganic silicon compoundto render a volume resistivity into a range of 1×10¹³-1×10¹⁵ Ω·cm.
 13. Amethod of producing an electrostatic chuck member according to claim 7,wherein the metallic electrode layer is formed by spraying one or moreof W, Al, Cu, Nb, Ta, Mo, Ni and an alloy containing one or more ofthese metal elements and has an oxygen content of not more than 2.0 wt %and a porosity of 1-7%.
 14. A method of producing an electrostatic chuckmember according to claim 7, wherein the metallic electrode layer isformed by spraying a metal spraying material having a particle sizesmaller than a particle size of a spraying material for the insulatinglayer.
 15. A method of producing an electrostatic chuck member accordingto claim 7, wherein a sealed layer is formed by applying a liquidorganic or inorganic silicon compound to a surface of the upperinsulating layer and/or the lower insulating layer and heating at120-350° C. for 1-5 hours.
 16. A method of producing an electrostaticchuck member according to claim 7, wherein a surface of the upperinsulating layer as a topcoat is mechanically polished to finish asurface roughness Ra to about 0.1-2.0 μm.